The present invention relates generally to a cushioning conversion machine and method. More particularly, the present invention relates to improved forming assemblies and/or forming steps for cushioning conversion machines and methods.
In the process of shipping an item from one location to another, a protective packaging material generally is placed in the shipping case, or box, to fill any voids, to cushion, to block and/or to brace the item during the shipping process. Various types of packing products have been used to pack articles in containers for shipment, including a crumpled paper cushioning product which is biodegradable, recyclable, and composed of a renewable resource, making it an environmentally responsible choice. A particularly desirable crumpled paper product is produced by crumpling one or more plies of sheet stock material, such as kraft paper. The sheet stock material is crumpled and folded upon itself to form a crumpled cushioning dunnage product having lateral pillow portions with a central band therebetween.
The conversion of multi-ply sheet material into a crumpled cushioning product may be accomplished by a cushioning conversion machine, such as those disclosed in U.S. Pat. Nos. 4,750,896; 4,884,999; and/or 5,607,383. (These patents are assigned to the assignee of the present application and their entire disclosures are incorporated by reference.) Each of the cushioning conversion, machines disclosed in the above-identified patents includes a conversion assembly which converts sheet stock material composed of one or more plies into a relatively less dense three-dimensional cushioning product. The conversion assembly includes a forming assembly which forms the sheet stock material into a strip having lateral pillow portions. The conversion assembly also includes a feeding assembly which is positioned downstream of the forming assembly and which pulls the stock material through the forming assembly and connects the strip along a central band.
The forming assemblies in the above-identified patents each comprise an external forming device such as a converging chute and an internal forming device such as a wire frame. The stock material travels through the external forming device and folds around the internal forming device to form the strip of cushioning. This inward folding may result in lateral regions of the stock material experiencing excessive edge tension which sometimes results in ripping or tearing of the stock material, particularly at the lateral edges. In addition, narrower widths of stock material have a tendency to shift laterally within the forming assembly, leading to inconsistently and often improperly formed cushioning products. This also leads to such problems as pads not forming properly from the first portion of a new paper supply, such as a stock roll.
In addition, the resiliency of the pillow portions encourages opening up or separation of the connected portions during manipulation of the dunnage product. The separation of the connected portions is commonly referred to as xe2x80x9cun-zipperingxe2x80x9d which generally begins at a longitudinal end of the dunnage product and progresses along the length of the connected portions. This problem also can be caused by the misalignment of the stock material in the forming assembly, as well as by inadequate connection of the overlapped portions of the stock material. This can occur when the overlapped portions have more layers of stock material than are necessary and/or when the overlapped portions include layers of stock material which have been crumpled and have a tendency to separate from adjacent layers.
Over the years, forming assemblies have been modified, improved or otherwise changed. Despite these past modifications, improvements and changes, a need remains for further improvements in cushioning conversion machines and methods with reduced edge tension and/or tearing associated therewith, while at the same time providing sufficient lateral control to form an acceptable cushioning product, and providing sufficient connection to maintain the shape of the cushioning product, with different widths and/or weights of stock material.
The present invention provides improved forming assemblies and/or forming steps for cushioning conversion machines and methods which address one or more of the aforementioned problems. In general, the present invention provides a cushioning conversion machine having a novel former around which a sheet material is folded to form an improved cushioning product. The former minimizes resistance to the flow of the stock material around the former while providing desirable cushioning properties in the formed cushioning product. The former softens the damming and/or reduces the temporary accumulation of the sheet material that was found to occur in prior art formers and provides for a smoother transition of the flow of crumpled sheet material around the former. The former also encourages the stock material to crumple in lateral regions and minimizes or restricts crumpling in a central region as the strip of cushioning is formed so that the feed assembly can form a better connection between the relatively uncrumpled layers of stock material in a portion of the strip of cushioning to maintain the shape of the formed cushioning product.
According to one aspect of the invention, a cushioning conversion machine for converting sheet stock material into a relatively lower density cushioning product as the sheet stock material moves through the machine from an upstream end toward a downstream end includes a feeding assembly and a forming assembly. The forming assembly includes a former with a top portion having a pair of generally longitudinally extending and coplanar converging lateral top edges. The former also has at least one lateral longitudinally spaced side edge depending from each of the top edges and inclined relative to the plane of the top edges.
According to one embodiment of the invention, the machine further includes support members which form the converging top edges and one or more ribs or rib portions forming the side edges. The support members may support mandrel portions which each have a greater cross-sectional area than the support members and which increase a height dimension and a width dimension of the former in the vicinity of the mandrel portions. In addition or in the alternative, the at least one rib may have a U-shape and/or may include side leg portions and bottom leg portions, the side leg portions forming the at least one inclined side edge. The bottom leg portions may form at least one bottom inclined edge extending from a vertical plane containing a longitudinal axis of the former, laterally outwardly and inclined toward the upstream end of the machine. Additionally or alternatively, the former may include a lateral guard plate mounted above the bottom leg portions. Additionally or alternatively, the former may include a base plate forming a substantially flat central surface extending substantially the length of the former. The base plate may be spaced relative to the chute to minimize crumpling of the central portion of the stock material. The forming assembly may additionally or alternatively include a pad width adjustment device which is selectively adjustable to change the width of the cushioning product by restricting the width or the height of a path of the sheet material.
According to another aspect of the invention, a cushioning conversion machine for converting sheet stock material into a relatively lower density cushioning product as the sheet stock material moves through the machine from an upstream end toward a downstream end includes a feeding assembly and a forming assembly. The forming assembly includes a former with a bottom plate and one or more generally coplanar longitudinally spaced bottom edges extending laterally outwardly from the bottom plate. The bottom edges are inclined relative to a vertical plane containing a longitudinal axis of the former. The bottom edges are inclined laterally outward and toward the upstream end of the machine.
According to yet another aspect of the invention, a method of converting sheet stock material having a central portion, lateral portions and lateral edge portions into a relatively lower density cushioning product, includes feeding the sheet stock material through a forming assembly, folding the lateral edge portions over the central portion to form an unconnected strip having lateral regions and a central region, causing alternate lateral side regions of the unconnected strip to dam behind inclined edges of a former to crumple the lateral side regions thereof, passing crumpled alternate lateral side regions thereof over the inclined edges; and connecting the central region thereof to form a connected strip.
According to another aspect of the invention, a former for use in a cushioning conversion machine to convert sheet stock material into a relatively lower density cushioning product as the stock material moves through the machine from an upstream end toward a downstream end, includes a top portion having a pair of generally longitudinally extending and coplanar converging lateral top edges. The former also includes one or more lateral longitudinally spaced side edges depending from the top edges and inclined relative to the plane of the top edges.
According to still another aspect of the invention, a cushioning conversion machine for converting sheet stock material into a relatively lower density cushioning product as the sheet stock material moves through the machine from an upstream end toward a downstream end. The machine includes a feeding mechanism for moving the sheet stock material through the machine, and a forming mechanism for forming the sheet stock material into the shape of the cushioning product. The forming mechanism includes a pair of generally longitudinally extending and coplanar converging lateral top edges, and one or more lateral longitudinally spaced side edges depending from the top edges and inclined relative to the plane of the top edges.
The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims. The following description and annexed drawings set forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.